Before he had his own TV show on Esquire Network — and even before he competed on Bravo’s “Top Chef” — Ilan Hall was challenging his fellow line cooks at Gramercy’s Casa Mono to culinary duels.

“We used to mess around with leftovers, and play around with little competitions, you know, mimicking ‘Iron Chef’ a bit,” Hall, 32, tells The Post.

He brought those behind-the-scenes competitions back when he opened his own restaurant, The Gorbals, in LA in 2009.

So, when the fledgling Esquire Network approached Hall about his own series, he knew exactly what he wanted to do.

“These competitions were something I was just doing. I didn’t see it as my big entrée back into TV or anything but I’m very comfortable with cameras,” the “Top Chef” Season 2 winner explains.

“Knife Fight,” which features award-winning chefs going head-to-head, creating meals out of a few secret ingredients, begins its second season Tuesday night.

The gritty, rowdy competition show is filmed at Hall’s downtown LA restaurant. There’s no glossy soundstage, no enticing cash prize — just bragging rights for the winner.

While the first season focused on LA-based competitors, Hall invited chefs from around the country this time around.

The premiere episode features Adam Sappington from Portland’s Country Cat and Michael Smith of Kansas City’s Michael Smith restaurant, who must make a meal out of semolina flour, a beef forequarter and a saw. Hall and a rotating panel of restaurateurs judge the dishes.

Along with the new season, the bespectacled chef is adding another major project to his plate — opening his second restaurant, also called The Gorbals, this month in the new Williamsburg Urban Outfitters concept store, Space Ninety 8.

The collaboration was a natural fit for Hall, who’d worked with the clothing store in the past, and whose wife is an executive there.

“They contacted me to consult on the café they wanted to do here at this new concept store in Williamsburg and I sort of jokingly said, ‘That’d be a great place for a restaurant.’ ” Hall says. “Then, the deal started happening very quickly.”

Hall recently relocated to South Williamsburg with his wife, Ayame Kawaguchi, and 3-year-old son, Theo, to focus full-time on the opening.

The Great Neck native says the heat is on with this second restaurant.

“New York diners are very fickle,” Hall says. “There is no room for error, no wiggle room, they’re on you like sharks — in a good way.”